When separating gaseous pollutants from process gases, such as flue gases from a coal- or oil-fired fired power plant, a method is frequently used, in which a lime-containing absorbent material is introduced into the process gas to react with the gaseous pollutants. When the absorbent material reacts with the gaseous pollutants, the gaseous pollutants are converted chemically or physically into dust, which is then separated in a filter. WO 96/16722 discloses a method, in which lime-containing dust is mixed with water in a mixer and then introduced into a contact reactor to react with gaseous pollutants in a flue gas. Then the dust is separated in a filter and recirculated to the mixer to be mixed once more with water and subsequently again be introduced into the contact reactor.
It has now been found that the mixing of water and dust in the mixer is sometimes less efficient, which results in less efficient removal of gaseous pollutants from the process gases.